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how can i generate enough heat to make toast from a 9 volt battery? Answered

 i want to make an altoids can toaster but im having trouble finding a safe way to generate enough heat from a 9 volt.... any ideas? the only way i know of how to make heat from a battery is by causing a short circuit which is dangerous, im sure theres a better way!


I read your question a few days ago and it stuck in my head.  I really hate when someone says something can't be done as in my mind it just means they haven't thought of a way to do it.  I have two possible suggestions, one which is certain to work, but probably is not what are looking for, and one which probably won't work, but is closer to what I think you want to do.

A 9volt battery will not generate the power needed to heat something in a traditional manner of heating a coil element... so you are going to have to find an exotic manner of producing the heat required.  One sure way to work is by using the battery to ignite something.  For example, if you touch a 9volt to a brillo pad, you will set it on fire.  The fine metallic fibers will ignite.  That heat would certainly toast your toast... but you probably don't want to be starting fires.

Another possibility to experiment with is tazering your bread by using a tazer circuit as shown on various instructables.  I suspect  that this will only toast a small section of the bread, but if you found a way to do this evenly all over the bread... theoretically... it might work...though probably not.  You may also want to investigate some Nasa technology used for heating satellites.  I know they have to keep them warm somehow with low voltage.

I'd mount a laser from a ps3 inside the altoids box and us it as a high powered laser pointer, there is a circuit for a laser driver for that particular diode - they say it is extremely powerfull and dangerous, just waiting for my parts to arrive in the post to actually test it myself, I reckon singing the surface of a slice of bread should be within it's capabilities and I'm sure you'll be able to modify the cicuit to run on a 9v battery.


8 years ago

I think the only way to get enough heat to make toast out of a 9V battery is to set it on fire...  and that's not a good idea.

Instead, I'd recommend a butane-powered torch that's aimed at a grille or griddle surface.  The griddle itself could be removed from the tin and spaced a few inches away, and the torch could be controlled using a valve mounted in the tin.

thanks for all the answers! really helped a lot

Sorry, but it can't work. There is just simply not enough power available in a 9 volt battery to toast the bread. It does take a fair bit of energy to toast bread.
Steveastrouk hit the nail on the head as to why. A 9 volt battery just doesn't have enough available energy.


8 years ago

Why not try something different, use the Altoids can as a type of folding vertical grill with W-shaped tray/base.  Make it so that you pour meths on the bottom tray with the bread standing vertically up.  The flames go up the side of the bread (not directly under or it'll burn [obviously]) Viola, toaster.

You can't. The battery cannot deliver enough current fast enough, even if you could make a suitable element. The "internal resistance" of a 9V cell usually limits the maximum output current to 3 or 4 amps, and that only for a few seconds.


Do you mean making enough heat to toast a slice of bread?  My electrical engineering is weak, but I think you might have some real difficulty. Looking at my toaster it needs to output roughly 40 Watts over 3 minutes to make toast.  (IF you take longer at lower power you won't toast anything.)  A 9V battery has about 650mAh, which give 5.85 Watt-hours. Or, in other words it would take 1/3 of a full charge to make a slice of toast.  This is where my knowledge fails, but I don't think you can discharge an average 9V battery that fast.

You might have to use they battery to charge a large capacitor or something to allow for a quicker, safer discharge.  But it would of courser be less efficient.

try using Nichrome wirse its used to make heating elements and gets hot with a reasonably small current, 9V battery will do fine.

Nicrome has a low resistance and will draw a large current from the battery which is then converted to heat, you may want to concider regulating the current some how but the details are really up to you, the following few sites should be helpful. Also you should be able to pick up good nichrome wire for around $4 for 20m.


Lots of heating info